#include <iostream>
using namespace std;

int dir[9][2] = {{0, 0}, {1, 2}, {1, -2}, {-1, 2}, {-1, -2}, {2, 1}, {2, -1}, {-2, 1}, {-2, -1}};

long long f[22][22];

int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  int n, m, x, y;
  cin >> n >> m >> x >> y;
  f[0][0] = 1;
  for (int i = 0; i <= n; i++) {
    for (int j = 0; j <= m; j++) {
      for (int k = 0; k < 9; k++) {
        if (x + dir[k][0] == i && y + dir[k][1] == j) {
          f[i][j] = 0;
        }
      }
      f[i + 1][j] += f[i][j];
      f[i][j + 1] += f[i][j];
    }
  }
  cout << f[n][m] << "\n";
  return 0;
}